(i) Field of the Invention
This invention relates to a device and method for superheating air conditioning refrigerant in a closed-loop air conditioning system, particularly an automotive air conditioning system.
(ii) Description of the Related Art
Air conditioning systems are almost universally sold with new automobiles, and it is well known that existing air conditioning systems substantially impact the fuel efficiency of motor vehicles. Improving the efficiency of air conditioning systems to conserve fuel is highly desirable, given the present high, rising costs of motor vehicle fuels as well as the general global environmental goals of reducing carbon dioxide emissions and other pollutants associated with the operation of motor vehicles. Motor vehicles generate large amounts of waste heat, which represents a significant fraction of the energy of combustion much of which is vented into the atmosphere through the operation of the exhaust manifold. Is it therefore highly desirable to utilize this heat to perform useful work, thereby preventing waste and improving the efficiency of motor vehicles.
In current vehicle air conditioning systems, the purpose of the compressor is to convert low-pressure, low-temperature refrigerant gas into high-pressure, high-temperature refrigerant gas before introducing the gas into a condenser, where it is cooled and converted into liquid refrigerant. In a typical closed-loop vehicle air conditioning system, the liquid refrigerant is then converted back to a gas in an evaporator. The expansion of the liquid into a gas results in cooling of the gas prior to its introduction into the passenger compartment of the vehicle. Through this closed cycle, refrigerant is continually recycled.
Typically, in a modern motor vehicle, the air conditioning compressor is linked to the drive shaft through a belt or other linking means, and the operation of the compressor is thereby operated by the direct application of work through the drive shaft. This system requires the combustion of fuels to provide the work necessary to operate the compressor. In these systems, the operation of the compressor can impact the fuel efficiency of a vehicle by as much as fifteen to twenty-five percent. It has been observed that in automobiles that have no automatic mechanism for increasing the energy consumption of the engine when the air conditioning system is activated that the revolutions-per-minute (rpm) may decrease as much as 25% when the compressor is activated.